[PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[Saravana Kannan]

Interconnects and interconnect paths quantify their performance levels in
terms of bandwidth and not in terms of frequency. So similar to how we have
frequency based OPP tables in DT and in the OPP framework, we need
bandwidth OPP table support in DT and in the OPP framework.

So with the DT bindings added in this patch series, the DT for a GPU
that does bandwidth voting from GPU to Cache and GPU to DDR would look
something like this:

gpu_cache_opp_table: gpu_cache_opp_table {
	compatible = "operating-points-v2";

	gpu_cache_3000: opp-3000 {
		opp-peak-KBps = <3000000>;
		opp-avg-KBps = <1000000>;
	};
	gpu_cache_6000: opp-6000 {
		opp-peak-KBps = <6000000>;
		opp-avg-KBps = <2000000>;
	};
	gpu_cache_9000: opp-9000 {
		opp-peak-KBps = <9000000>;
		opp-avg-KBps = <9000000>;
	};
};

gpu_ddr_opp_table: gpu_ddr_opp_table {
	compatible = "operating-points-v2";

	gpu_ddr_1525: opp-1525 {
		opp-peak-KBps = <1525000>;
		opp-avg-KBps = <452000>;
	};
	gpu_ddr_3051: opp-3051 {
		opp-peak-KBps = <3051000>;
		opp-avg-KBps = <915000>;
	};
	gpu_ddr_7500: opp-7500 {
		opp-peak-KBps = <7500000>;
		opp-avg-KBps = <3000000>;
	};
};

gpu_opp_table: gpu_opp_table {
	compatible = "operating-points-v2";
	opp-shared;

	opp-200000000 {
		opp-hz = /bits/ 64 <200000000>;
	};
	opp-400000000 {
		opp-hz = /bits/ 64 <400000000>;
	};
};

gpu@7864000 {
	...
	operating-points-v2 = <&gpu_opp_table>, <&gpu_cache_opp_table>, <&gpu_ddr_opp_table>;
	...
};

v1 -> v3:
- Lots of patch additions that were later dropped
v3 -> v4:
- Fixed typo bugs pointed out by Sibi.
- Fixed bug that incorrectly reset rate to 0 all the time
- Added units documentation
- Dropped interconnect-opp-table property and related changes

Cheers,
Saravana

Saravana Kannan (3):
  dt-bindings: opp: Introduce opp-peak-KBps and opp-avg-KBps bindings
  OPP: Add support for bandwidth OPP tables
  OPP: Add helper function for bandwidth OPP tables

 Documentation/devicetree/bindings/opp/opp.txt | 15 ++++--
 .../devicetree/bindings/property-units.txt    |  4 ++
 drivers/opp/core.c                            | 51 +++++++++++++++++++
 drivers/opp/of.c                              | 41 +++++++++++----
 drivers/opp/opp.h                             |  4 +-
 include/linux/pm_opp.h                        | 19 +++++++
 6 files changed, 121 insertions(+), 13 deletions(-)

-- 
2.22.0.709.g102302147b-goog

[PATCH v4 1/3] dt-bindings: opp: Introduce opp-peak-KBps and opp-avg-KBps bindings

[Saravana Kannan]

Interconnects often quantify their performance points in terms of
bandwidth. So, add opp-peak-KBps (required) and opp-avg-KBps (optional) to
allow specifying Bandwidth OPP tables in DT.

opp-peak-KBps is a required property that replace opp-hz for Bandwidth OPP
tables.

opp-avg-KBps is an optional property that can be used in Bandwidth OPP
tables.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 Documentation/devicetree/bindings/opp/opp.txt     | 15 ++++++++++++---
 .../devicetree/bindings/property-units.txt        |  4 ++++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
index 76b6c79604a5..b1eb49d6eab0 100644
--- a/Documentation/devicetree/bindings/opp/opp.txt
+++ b/Documentation/devicetree/bindings/opp/opp.txt
@@ -83,9 +83,14 @@ properties.
 
 Required properties:
 - opp-hz: Frequency in Hz, expressed as a 64-bit big-endian integer. This is a
-  required property for all device nodes but devices like power domains. The
-  power domain nodes must have another (implementation dependent) property which
-  uniquely identifies the OPP nodes.
+  required property for all device nodes but for devices like power domains or
+  bandwidth opp tables. The power domain nodes must have another (implementation
+  dependent) property which uniquely identifies the OPP nodes. The interconnect
+  opps are required to have the opp-peak-KBps property.
+
+- opp-peak-KBps: Peak bandwidth in kilobytes per second, expressed as a 32-bit
+  big-endian integer. This is a required property for all devices that don't
+  have opp-hz. For example, bandwidth OPP tables for interconnect paths.
 
 Optional properties:
 - opp-microvolt: voltage in micro Volts.
@@ -132,6 +137,10 @@ Optional properties:
 - opp-level: A value representing the performance level of the device,
   expressed as a 32-bit integer.
 
+- opp-avg-KBps: Average bandwidth in kilobytes per second, expressed as a
+  32-bit big-endian integer. This property is only meaningful in OPP tables
+  where opp-peak-KBps is present.
+
 - clock-latency-ns: Specifies the maximum possible transition latency (in
   nanoseconds) for switching to this OPP from any other OPP.
 
diff --git a/Documentation/devicetree/bindings/property-units.txt b/Documentation/devicetree/bindings/property-units.txt
index e9b8360b3288..ef4c4a199efa 100644
--- a/Documentation/devicetree/bindings/property-units.txt
+++ b/Documentation/devicetree/bindings/property-units.txt
@@ -41,3 +41,7 @@ Temperature
 Pressure
 ----------------------------------------
 -kpascal	: kilopascal
+
+Throughput
+----------------------------------------
+-KBps		: kilobytes per second
-- 
2.22.0.709.g102302147b-goog

[PATCH v4 2/3] OPP: Add support for bandwidth OPP tables

[Saravana Kannan]

Not all devices quantify their performance points in terms of frequency.
Devices like interconnects quantify their performance points in terms of
bandwidth. We need a way to represent these bandwidth levels in OPP. So,
add support for parsing bandwidth OPPs from DT.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/opp/of.c  | 41 ++++++++++++++++++++++++++++++++---------
 drivers/opp/opp.h |  4 +++-
 2 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/drivers/opp/of.c b/drivers/opp/of.c
index b313aca9894f..ac73512f4416 100644
--- a/drivers/opp/of.c
+++ b/drivers/opp/of.c
@@ -523,6 +523,35 @@ void dev_pm_opp_of_remove_table(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_of_remove_table);
 
+static int _read_opp_key(struct dev_pm_opp *new_opp, struct device_node *np)
+{
+	int ret;
+	u64 rate;
+	u32 bw;
+
+	ret = of_property_read_u64(np, "opp-hz", &rate);
+	if (!ret) {
+		/*
+		 * Rate is defined as an unsigned long in clk API, and so
+		 * casting explicitly to its type. Must be fixed once rate is 64
+		 * bit guaranteed in clk API.
+		 */
+		new_opp->rate = (unsigned long)rate;
+		return 0;
+	}
+
+	ret = of_property_read_u32(np, "opp-peak-KBps", &bw);
+	if (ret)
+		return ret;
+	new_opp->rate = (unsigned long) bw;
+
+	ret = of_property_read_u32(np, "opp-avg-KBps", &bw);
+	if (!ret)
+		new_opp->avg_bw = (unsigned long) bw;
+
+	return 0;
+}
+
 /**
  * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
  * @opp_table:	OPP table
@@ -560,22 +589,16 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
 	if (!new_opp)
 		return ERR_PTR(-ENOMEM);
 
-	ret = of_property_read_u64(np, "opp-hz", &rate);
+	ret = _read_opp_key(new_opp, np);
 	if (ret < 0) {
 		/* "opp-hz" is optional for devices like power domains. */
 		if (!opp_table->is_genpd) {
-			dev_err(dev, "%s: opp-hz not found\n", __func__);
+			dev_err(dev, "%s: opp-hz or opp-peak-bw not found\n",
+				__func__);
 			goto free_opp;
 		}
 
 		rate_not_available = true;
-	} else {
-		/*
-		 * Rate is defined as an unsigned long in clk API, and so
-		 * casting explicitly to its type. Must be fixed once rate is 64
-		 * bit guaranteed in clk API.
-		 */
-		new_opp->rate = (unsigned long)rate;
 	}
 
 	of_property_read_u32(np, "opp-level", &new_opp->level);
diff --git a/drivers/opp/opp.h b/drivers/opp/opp.h
index 01a500e2c40a..6bb238af9cac 100644
--- a/drivers/opp/opp.h
+++ b/drivers/opp/opp.h
@@ -56,7 +56,8 @@ extern struct list_head opp_tables;
  * @turbo:	true if turbo (boost) OPP
  * @suspend:	true if suspend OPP
  * @pstate: Device's power domain's performance state.
- * @rate:	Frequency in hertz
+ * @rate:	Frequency in hertz OR Peak bandwidth in kilobytes per second
+ * @avg_bw:	Average bandwidth in kilobytes per second
  * @level:	Performance level
  * @supplies:	Power supplies voltage/current values
  * @clock_latency_ns: Latency (in nanoseconds) of switching to this OPP's
@@ -78,6 +79,7 @@ struct dev_pm_opp {
 	bool suspend;
 	unsigned int pstate;
 	unsigned long rate;
+	unsigned long avg_bw;
 	unsigned int level;
 
 	struct dev_pm_opp_supply *supplies;
-- 
2.22.0.709.g102302147b-goog

[PATCH v4 3/3] OPP: Add helper function for bandwidth OPP tables

[Saravana Kannan]

The frequency OPP tables have helper functions to search for entries in the
table based on frequency and get the frequency values for a given (or
suspend) OPP entry.

Add similar helper functions for bandwidth OPP tables to search for entries
in the table based on peak bandwidth and to get the peak and average
bandwidth for a given (or suspend) OPP entry.

Signed-off-by: Saravana Kannan <saravanak@google.com>
---
 drivers/opp/core.c     | 51 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/pm_opp.h | 19 ++++++++++++++++
 2 files changed, 70 insertions(+)

diff --git a/drivers/opp/core.c b/drivers/opp/core.c
index c094d5d20fd7..b36bc69341dc 100644
--- a/drivers/opp/core.c
+++ b/drivers/opp/core.c
@@ -127,6 +127,29 @@ unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);
 
+/**
+ * dev_pm_opp_get_bw() - Gets the bandwidth corresponding to an available opp
+ * @opp:	opp for which frequency has to be returned for
+ * @avg_bw:	Pointer where the corresponding average bandwidth is stored.
+ *		Can be NULL.
+ *
+ * Return: Peak bandwidth in KBps corresponding to the opp, else
+ * return 0
+ */
+unsigned long dev_pm_opp_get_bw(struct dev_pm_opp *opp, unsigned long *avg_bw)
+{
+	if (IS_ERR_OR_NULL(opp) || !opp->available) {
+		pr_err("%s: Invalid parameters\n", __func__);
+		return 0;
+	}
+
+	if (avg_bw)
+		*avg_bw = opp->avg_bw;
+
+	return opp->rate;
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_bw);
+
 /**
  * dev_pm_opp_get_level() - Gets the level corresponding to an available opp
  * @opp:	opp for which level value has to be returned for
@@ -299,6 +322,34 @@ unsigned long dev_pm_opp_get_suspend_opp_freq(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_get_suspend_opp_freq);
 
+/**
+ * dev_pm_opp_get_suspend_opp_bw() - Get peak bandwidth of suspend opp in KBps
+ * @dev:	device for which we do this operation
+ * @avg_bw:	Pointer where the corresponding average bandwidth is stored.
+ *		Can be NULL.
+ *
+ * Return: This function returns the peak bandwidth of the OPP marked as
+ * suspend_opp if one is available, else returns 0;
+ */
+unsigned long dev_pm_opp_get_suspend_opp_bw(struct device *dev,
+					    unsigned long *avg_bw)
+{
+	struct opp_table *opp_table;
+	unsigned long peak_bw = 0;
+
+	opp_table = _find_opp_table(dev);
+	if (IS_ERR(opp_table))
+		return 0;
+
+	if (opp_table->suspend_opp && opp_table->suspend_opp->available)
+		peak_bw = dev_pm_opp_get_bw(opp_table->suspend_opp, avg_bw);
+
+	dev_pm_opp_put_opp_table(opp_table);
+
+	return peak_bw;
+}
+EXPORT_SYMBOL_GPL(dev_pm_opp_get_suspend_opp_bw);
+
 int _get_opp_count(struct opp_table *opp_table)
 {
 	struct dev_pm_opp *opp;
diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
index af5021f27cb7..799b1defe1f7 100644
--- a/include/linux/pm_opp.h
+++ b/include/linux/pm_opp.h
@@ -82,6 +82,7 @@ void dev_pm_opp_put_opp_table(struct opp_table *opp_table);
 unsigned long dev_pm_opp_get_voltage(struct dev_pm_opp *opp);
 
 unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp);
+unsigned long dev_pm_opp_get_bw(struct dev_pm_opp *opp, unsigned long *avg_bw);
 
 unsigned int dev_pm_opp_get_level(struct dev_pm_opp *opp);
 
@@ -92,6 +93,8 @@ unsigned long dev_pm_opp_get_max_clock_latency(struct device *dev);
 unsigned long dev_pm_opp_get_max_volt_latency(struct device *dev);
 unsigned long dev_pm_opp_get_max_transition_latency(struct device *dev);
 unsigned long dev_pm_opp_get_suspend_opp_freq(struct device *dev);
+unsigned long dev_pm_opp_get_suspend_opp_bw(struct device *dev,
+					    unsigned long *avg_bw);
 
 struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
 					      unsigned long freq,
@@ -158,6 +161,11 @@ static inline unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
 {
 	return 0;
 }
+static inline unsigned long dev_pm_opp_get_bw(struct dev_pm_opp *opp,
+					      unsigned long *avg_bw)
+{
+	return 0;
+}
 
 static inline unsigned int dev_pm_opp_get_level(struct dev_pm_opp *opp)
 {
@@ -194,6 +202,12 @@ static inline unsigned long dev_pm_opp_get_suspend_opp_freq(struct device *dev)
 	return 0;
 }
 
+static inline unsigned long dev_pm_opp_get_suspend_opp_bw(struct device *dev,
+							  unsigned long *avg_bw)
+{
+	return 0;
+}
+
 static inline struct dev_pm_opp *dev_pm_opp_find_freq_exact(struct device *dev,
 					unsigned long freq, bool available)
 {
@@ -329,6 +343,11 @@ static inline void dev_pm_opp_cpumask_remove_table(const struct cpumask *cpumask
 
 #endif		/* CONFIG_PM_OPP */
 
+#define dev_pm_opp_find_peak_bw_exact	dev_pm_opp_find_freq_exact
+#define dev_pm_opp_find_peak_bw_floor	dev_pm_opp_find_freq_floor
+#define dev_pm_opp_find_peak_bw_ceil_by_volt dev_pm_opp_find_freq_ceil_by_volt
+#define dev_pm_opp_find_peak_bw_ceil	dev_pm_opp_find_freq_ceil
+
 #if defined(CONFIG_PM_OPP) && defined(CONFIG_OF)
 int dev_pm_opp_of_add_table(struct device *dev);
 int dev_pm_opp_of_add_table_indexed(struct device *dev, int index);
-- 
2.22.0.709.g102302147b-goog

Re: [PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[Viresh Kumar]

On 26-07-19, 16:15, Saravana Kannan wrote:
> Interconnects and interconnect paths quantify their performance levels in
> terms of bandwidth and not in terms of frequency. So similar to how we have
> frequency based OPP tables in DT and in the OPP framework, we need
> bandwidth OPP table support in DT and in the OPP framework.
> 
> So with the DT bindings added in this patch series, the DT for a GPU
> that does bandwidth voting from GPU to Cache and GPU to DDR would look
> something like this:
> 
> gpu_cache_opp_table: gpu_cache_opp_table {
> 	compatible = "operating-points-v2";
> 
> 	gpu_cache_3000: opp-3000 {
> 		opp-peak-KBps = <3000000>;
> 		opp-avg-KBps = <1000000>;
> 	};
> 	gpu_cache_6000: opp-6000 {
> 		opp-peak-KBps = <6000000>;
> 		opp-avg-KBps = <2000000>;
> 	};
> 	gpu_cache_9000: opp-9000 {
> 		opp-peak-KBps = <9000000>;
> 		opp-avg-KBps = <9000000>;
> 	};
> };
> 
> gpu_ddr_opp_table: gpu_ddr_opp_table {
> 	compatible = "operating-points-v2";
> 
> 	gpu_ddr_1525: opp-1525 {
> 		opp-peak-KBps = <1525000>;
> 		opp-avg-KBps = <452000>;
> 	};
> 	gpu_ddr_3051: opp-3051 {
> 		opp-peak-KBps = <3051000>;
> 		opp-avg-KBps = <915000>;
> 	};
> 	gpu_ddr_7500: opp-7500 {
> 		opp-peak-KBps = <7500000>;
> 		opp-avg-KBps = <3000000>;
> 	};
> };
> 
> gpu_opp_table: gpu_opp_table {
> 	compatible = "operating-points-v2";
> 	opp-shared;
> 
> 	opp-200000000 {
> 		opp-hz = /bits/ 64 <200000000>;
> 	};
> 	opp-400000000 {
> 		opp-hz = /bits/ 64 <400000000>;
> 	};
> };
> 
> gpu@7864000 {
> 	...
> 	operating-points-v2 = <&gpu_opp_table>, <&gpu_cache_opp_table>, <&gpu_ddr_opp_table>;
> 	...
> };

One feedback I missed giving earlier. Will it be possible to get some
user code merged along with this ? I want to make sure anything we add
ends up getting used.

That also helps understanding the problems you are facing in a better
way, i.e. with real examples.

-- 
viresh

Re: [PATCH v4 1/3] dt-bindings: opp: Introduce opp-peak-KBps and opp-avg-KBps bindings

[Stephen Boyd]

Quoting Saravana Kannan (2019-07-26 16:15:55)
> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> index 76b6c79604a5..b1eb49d6eab0 100644
> --- a/Documentation/devicetree/bindings/opp/opp.txt
> +++ b/Documentation/devicetree/bindings/opp/opp.txt
> @@ -83,9 +83,14 @@ properties.
>  
>  Required properties:
>  - opp-hz: Frequency in Hz, expressed as a 64-bit big-endian integer. This is a
> -  required property for all device nodes but devices like power domains. The
> -  power domain nodes must have another (implementation dependent) property which
> -  uniquely identifies the OPP nodes.
> +  required property for all device nodes but for devices like power domains or

s/but/except/

> +  bandwidth opp tables. The power domain nodes must have another (implementation
> +  dependent) property which uniquely identifies the OPP nodes. The interconnect
> +  opps are required to have the opp-peak-KBps property.
> +
> +- opp-peak-KBps: Peak bandwidth in kilobytes per second, expressed as a 32-bit
> +  big-endian integer. This is a required property for all devices that don't
> +  have opp-hz. For example, bandwidth OPP tables for interconnect paths.
>  
>  Optional properties:
>  - opp-microvolt: voltage in micro Volts.
> @@ -132,6 +137,10 @@ Optional properties:
>  - opp-level: A value representing the performance level of the device,
>    expressed as a 32-bit integer.
>  
> +- opp-avg-KBps: Average bandwidth in kilobytes per second, expressed as a

Shouldn't that be a lower case k? kBps?

> +  32-bit big-endian integer. This property is only meaningful in OPP tables
> +  where opp-peak-KBps is present.
> +
>  - clock-latency-ns: Specifies the maximum possible transition latency (in
>    nanoseconds) for switching to this OPP from any other OPP.
>  
> diff --git a/Documentation/devicetree/bindings/property-units.txt b/Documentation/devicetree/bindings/property-units.txt
> index e9b8360b3288..ef4c4a199efa 100644
> --- a/Documentation/devicetree/bindings/property-units.txt
> +++ b/Documentation/devicetree/bindings/property-units.txt
> @@ -41,3 +41,7 @@ Temperature
>  Pressure
>  ----------------------------------------
>  -kpascal       : kilopascal
> +
> +Throughput
> +----------------------------------------
> +-KBps          : kilobytes per second

Same comment.

Re: [PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[Saravana Kannan]

On Mon, Jul 29, 2019 at 2:35 AM Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 26-07-19, 16:15, Saravana Kannan wrote:
> > Interconnects and interconnect paths quantify their performance levels in
> > terms of bandwidth and not in terms of frequency. So similar to how we have
> > frequency based OPP tables in DT and in the OPP framework, we need
> > bandwidth OPP table support in DT and in the OPP framework.
> >
> > So with the DT bindings added in this patch series, the DT for a GPU
> > that does bandwidth voting from GPU to Cache and GPU to DDR would look
> > something like this:
> >
> > gpu_cache_opp_table: gpu_cache_opp_table {
> >       compatible = "operating-points-v2";
> >
> >       gpu_cache_3000: opp-3000 {
> >               opp-peak-KBps = <3000000>;
> >               opp-avg-KBps = <1000000>;
> >       };
> >       gpu_cache_6000: opp-6000 {
> >               opp-peak-KBps = <6000000>;
> >               opp-avg-KBps = <2000000>;
> >       };
> >       gpu_cache_9000: opp-9000 {
> >               opp-peak-KBps = <9000000>;
> >               opp-avg-KBps = <9000000>;
> >       };
> > };
> >
> > gpu_ddr_opp_table: gpu_ddr_opp_table {
> >       compatible = "operating-points-v2";
> >
> >       gpu_ddr_1525: opp-1525 {
> >               opp-peak-KBps = <1525000>;
> >               opp-avg-KBps = <452000>;
> >       };
> >       gpu_ddr_3051: opp-3051 {
> >               opp-peak-KBps = <3051000>;
> >               opp-avg-KBps = <915000>;
> >       };
> >       gpu_ddr_7500: opp-7500 {
> >               opp-peak-KBps = <7500000>;
> >               opp-avg-KBps = <3000000>;
> >       };
> > };
> >
> > gpu_opp_table: gpu_opp_table {
> >       compatible = "operating-points-v2";
> >       opp-shared;
> >
> >       opp-200000000 {
> >               opp-hz = /bits/ 64 <200000000>;
> >       };
> >       opp-400000000 {
> >               opp-hz = /bits/ 64 <400000000>;
> >       };
> > };
> >
> > gpu@7864000 {
> >       ...
> >       operating-points-v2 = <&gpu_opp_table>, <&gpu_cache_opp_table>, <&gpu_ddr_opp_table>;
> >       ...
> > };
>
> One feedback I missed giving earlier. Will it be possible to get some
> user code merged along with this ? I want to make sure anything we add
> ends up getting used.

Sibi might be working on doing that for the SDM845 CPUfreq driver.
Georgi could also change his GPU driver use case to use this BW OPP
table and required-opps.

The problem is that people don't want to start using this until we
decide on the DT representation. So it's like a chicken and egg
situation.

-Saravana

Re: [PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[Viresh Kumar]

On 29-07-19, 13:16, Saravana Kannan wrote:
> Sibi might be working on doing that for the SDM845 CPUfreq driver.
> Georgi could also change his GPU driver use case to use this BW OPP
> table and required-opps.
> 
> The problem is that people don't want to start using this until we
> decide on the DT representation. So it's like a chicken and egg
> situation.

Yeah, I agree to that.

@Georgi and @Sibi: This is your chance to speak up about the proposal
from Saravana and if you find anything wrong with them. And specially
that it is mostly about interconnects here, I would like to have an
explicit Ack from Georgi on this.

And if you guys are all okay about this then please at least commit
that you will convert your stuff based on this in coming days.

-- 
viresh

Re: [PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[Sibi Sankar]

Hey Viresh,

On 7/30/19 8:16 AM, Viresh Kumar wrote:
> On 29-07-19, 13:16, Saravana Kannan wrote:
>> Sibi might be working on doing that for the SDM845 CPUfreq driver.
>> Georgi could also change his GPU driver use case to use this BW OPP
>> table and required-opps.
>>
>> The problem is that people don't want to start using this until we
>> decide on the DT representation. So it's like a chicken and egg
>> situation.
> 
> Yeah, I agree to that.
> 
> @Georgi and @Sibi: This is your chance to speak up about the proposal
> from Saravana and if you find anything wrong with them. And specially
> that it is mostly about interconnects here, I would like to have an
> explicit Ack from Georgi on this.
> 
> And if you guys are all okay about this then please at least commit
> that you will convert your stuff based on this in coming days.

I've been using both Saravana's and Georgi's series for a while
now to scale DDR and L3 on SDM845. There is currently no consensus
as to where the votes are to be actuated from, hence couldn't post
anything out.

DCVS based on Saravana's series + passive governor:
https://github.com/QuinAsura/linux/tree/lnext-072619-SK-series

DCVS based on Georgi's series: (I had already posted this out)
https://github.com/QuinAsura/linux/tree/lnext-072619-GJ-series

-- 
Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc, is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[Saravana Kannan]

On Mon, Jul 29, 2019 at 10:28 PM Sibi Sankar <sibis@codeaurora.org> wrote:
>
> Hey Viresh,
>
> On 7/30/19 8:16 AM, Viresh Kumar wrote:
> > On 29-07-19, 13:16, Saravana Kannan wrote:
> >> Sibi might be working on doing that for the SDM845 CPUfreq driver.
> >> Georgi could also change his GPU driver use case to use this BW OPP
> >> table and required-opps.
> >>
> >> The problem is that people don't want to start using this until we
> >> decide on the DT representation. So it's like a chicken and egg
> >> situation.
> >
> > Yeah, I agree to that.
> >
> > @Georgi and @Sibi: This is your chance to speak up about the proposal
> > from Saravana and if you find anything wrong with them. And specially
> > that it is mostly about interconnects here, I would like to have an
> > explicit Ack from Georgi on this.
> >
> > And if you guys are all okay about this then please at least commit
> > that you will convert your stuff based on this in coming days.
>
> I've been using both Saravana's and Georgi's series for a while
> now to scale DDR and L3 on SDM845. There is currently no consensus
> as to where the votes are to be actuated from, hence couldn't post
> anything out.
>
> DCVS based on Saravana's series + passive governor:
> https://github.com/QuinAsura/linux/tree/lnext-072619-SK-series

Thanks Sibi! You might want to convert your patches so that until the
passive governor is ready, you just look up the required opps and vote
for BW directly from the cpufreq driver. Once devfreq governor is
ready, you can switch to it.

-Saravana

>
> DCVS based on Georgi's series: (I had already posted this out)
> https://github.com/QuinAsura/linux/tree/lnext-072619-GJ-series
>
> --
> Qualcomm Innovation Center, Inc.
> Qualcomm Innovation Center, Inc, is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project

Re: [PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[Sibi Sankar]

On 7/30/19 11:23 AM, Saravana Kannan wrote:
> On Mon, Jul 29, 2019 at 10:28 PM Sibi Sankar <sibis@codeaurora.org> wrote:
>>
>> Hey Viresh,
>>
>> On 7/30/19 8:16 AM, Viresh Kumar wrote:
>>> On 29-07-19, 13:16, Saravana Kannan wrote:
>>>> Sibi might be working on doing that for the SDM845 CPUfreq driver.
>>>> Georgi could also change his GPU driver use case to use this BW OPP
>>>> table and required-opps.
>>>>
>>>> The problem is that people don't want to start using this until we
>>>> decide on the DT representation. So it's like a chicken and egg
>>>> situation.
>>>
>>> Yeah, I agree to that.
>>>
>>> @Georgi and @Sibi: This is your chance to speak up about the proposal
>>> from Saravana and if you find anything wrong with them. And specially
>>> that it is mostly about interconnects here, I would like to have an
>>> explicit Ack from Georgi on this.
>>>
>>> And if you guys are all okay about this then please at least commit
>>> that you will convert your stuff based on this in coming days.
>>
>> I've been using both Saravana's and Georgi's series for a while
>> now to scale DDR and L3 on SDM845. There is currently no consensus
>> as to where the votes are to be actuated from, hence couldn't post
>> anything out.
>>
>> DCVS based on Saravana's series + passive governor:
>> https://github.com/QuinAsura/linux/tree/lnext-072619-SK-series
> 
> Thanks Sibi! You might want to convert your patches so that until the
> passive governor is ready, you just look up the required opps and vote
> for BW directly from the cpufreq driver. Once devfreq governor is
> ready, you can switch to it.

Sure I'll do that.

> 
> -Saravana
> 
>>
>> DCVS based on Georgi's series: (I had already posted this out)
>> https://github.com/QuinAsura/linux/tree/lnext-072619-GJ-series
>>
>> --
>> Qualcomm Innovation Center, Inc.
>> Qualcomm Innovation Center, Inc, is a member of Code Aurora Forum,
>> a Linux Foundation Collaborative Project

-- 
Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc, is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH v4 0/3] Introduce Bandwidth OPPs for interconnects

[Georgi Djakov]

On 7/30/19 05:46, Viresh Kumar wrote:
> On 29-07-19, 13:16, Saravana Kannan wrote:
>> Sibi might be working on doing that for the SDM845 CPUfreq driver.
>> Georgi could also change his GPU driver use case to use this BW OPP
>> table and required-opps.
>>
>> The problem is that people don't want to start using this until we
>> decide on the DT representation. So it's like a chicken and egg
>> situation.
> 
> Yeah, I agree to that.
> 
> @Georgi and @Sibi: This is your chance to speak up about the proposal
> from Saravana and if you find anything wrong with them. And specially
> that it is mostly about interconnects here, I would like to have an
> explicit Ack from Georgi on this.
> 
> And if you guys are all okay about this then please at least commit
> that you will convert your stuff based on this in coming days.

Looks fine to me. I am already doing some testing with this patchset.
However, as Stephen already pointed out, we should s/KBps/kBps/.

Thanks,
Georgi

Re: [PATCH v4 2/3] OPP: Add support for bandwidth OPP tables

[Georgi Djakov]

Hi Saravana,

On 7/27/19 02:15, Saravana Kannan wrote:
> Not all devices quantify their performance points in terms of frequency.
> Devices like interconnects quantify their performance points in terms of
> bandwidth. We need a way to represent these bandwidth levels in OPP. So,
> add support for parsing bandwidth OPPs from DT.
> 
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> ---
>  drivers/opp/of.c  | 41 ++++++++++++++++++++++++++++++++---------
>  drivers/opp/opp.h |  4 +++-
>  2 files changed, 35 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> index b313aca9894f..ac73512f4416 100644
> --- a/drivers/opp/of.c
> +++ b/drivers/opp/of.c
> @@ -523,6 +523,35 @@ void dev_pm_opp_of_remove_table(struct device *dev)
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_opp_of_remove_table);
>  
> +static int _read_opp_key(struct dev_pm_opp *new_opp, struct device_node *np)
> +{
> +	int ret;
> +	u64 rate;
> +	u32 bw;
> +
> +	ret = of_property_read_u64(np, "opp-hz", &rate);
> +	if (!ret) {
> +		/*
> +		 * Rate is defined as an unsigned long in clk API, and so
> +		 * casting explicitly to its type. Must be fixed once rate is 64
> +		 * bit guaranteed in clk API.
> +		 */
> +		new_opp->rate = (unsigned long)rate;
> +		return 0;

So we can't have a single OPP table with both frequency and bandwidth?

> +	}
> +
> +	ret = of_property_read_u32(np, "opp-peak-KBps", &bw);
> +	if (ret)
> +		return ret;
> +	new_opp->rate = (unsigned long) bw;
> +
> +	ret = of_property_read_u32(np, "opp-avg-KBps", &bw);
> +	if (!ret)
> +		new_opp->avg_bw = (unsigned long) bw;
> +
> +	return 0;
> +}
> +
>  /**
>   * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
>   * @opp_table:	OPP table
> @@ -560,22 +589,16 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
>  	if (!new_opp)
>  		return ERR_PTR(-ENOMEM);
>  
> -	ret = of_property_read_u64(np, "opp-hz", &rate);
> +	ret = _read_opp_key(new_opp, np);
>  	if (ret < 0) {
>  		/* "opp-hz" is optional for devices like power domains. */
>  		if (!opp_table->is_genpd) {
> -			dev_err(dev, "%s: opp-hz not found\n", __func__);
> +			dev_err(dev, "%s: opp-hz or opp-peak-bw not found\n",

s/opp-peak-bw/opp-peak-kBps/

Thanks,
Georgi

Re: [PATCH v4 2/3] OPP: Add support for bandwidth OPP tables

[Saravana Kannan]

On Wed, Aug 7, 2019 at 5:53 AM Georgi Djakov <georgi.djakov@linaro.org> wrote:
>
> Hi Saravana,
>
> On 7/27/19 02:15, Saravana Kannan wrote:
> > Not all devices quantify their performance points in terms of frequency.
> > Devices like interconnects quantify their performance points in terms of
> > bandwidth. We need a way to represent these bandwidth levels in OPP. So,
> > add support for parsing bandwidth OPPs from DT.
> >
> > Signed-off-by: Saravana Kannan <saravanak@google.com>
> > ---
> >  drivers/opp/of.c  | 41 ++++++++++++++++++++++++++++++++---------
> >  drivers/opp/opp.h |  4 +++-
> >  2 files changed, 35 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> > index b313aca9894f..ac73512f4416 100644
> > --- a/drivers/opp/of.c
> > +++ b/drivers/opp/of.c
> > @@ -523,6 +523,35 @@ void dev_pm_opp_of_remove_table(struct device *dev)
> >  }
> >  EXPORT_SYMBOL_GPL(dev_pm_opp_of_remove_table);
> >
> > +static int _read_opp_key(struct dev_pm_opp *new_opp, struct device_node *np)
> > +{
> > +     int ret;
> > +     u64 rate;
> > +     u32 bw;
> > +
> > +     ret = of_property_read_u64(np, "opp-hz", &rate);
> > +     if (!ret) {
> > +             /*
> > +              * Rate is defined as an unsigned long in clk API, and so
> > +              * casting explicitly to its type. Must be fixed once rate is 64
> > +              * bit guaranteed in clk API.
> > +              */
> > +             new_opp->rate = (unsigned long)rate;
> > +             return 0;
>
> So we can't have a single OPP table with both frequency and bandwidth?

Right, because we can have only 1 "key" for the OPP table. Having more
than one "key" for an OPP table makes a lot of things pretty messy.
Most of the helper functions need to be rewritten to say which key is
being referred to when searching. A lot of the error checking when
creating OPP tables becomes convoluted -- can we allow more than one
OPP entry with the same frequency just because the opp-peak-kBps is
different? Etc. Seems like a lot of code change for something that I
don't think is a very useful.

Also, an OPP table is either going to represent performance levels of
a clock domain (opp-hz) or the performance levels of an interconnect
path (opp-peak-kBps) or an OPP table for genpd. Mixing them all up is
just going to make it convoluted with not enough benefit or use case
that can't be handled as is (separate BW and freq OPP tables).

> > +     }
> > +
> > +     ret = of_property_read_u32(np, "opp-peak-KBps", &bw);
> > +     if (ret)
> > +             return ret;
> > +     new_opp->rate = (unsigned long) bw;
> > +
> > +     ret = of_property_read_u32(np, "opp-avg-KBps", &bw);
> > +     if (!ret)
> > +             new_opp->avg_bw = (unsigned long) bw;
> > +
> > +     return 0;
> > +}
> > +
> >  /**
> >   * _opp_add_static_v2() - Allocate static OPPs (As per 'v2' DT bindings)
> >   * @opp_table:       OPP table
> > @@ -560,22 +589,16 @@ static struct dev_pm_opp *_opp_add_static_v2(struct opp_table *opp_table,
> >       if (!new_opp)
> >               return ERR_PTR(-ENOMEM);
> >
> > -     ret = of_property_read_u64(np, "opp-hz", &rate);
> > +     ret = _read_opp_key(new_opp, np);
> >       if (ret < 0) {
> >               /* "opp-hz" is optional for devices like power domains. */
> >               if (!opp_table->is_genpd) {
> > -                     dev_err(dev, "%s: opp-hz not found\n", __func__);
> > +                     dev_err(dev, "%s: opp-hz or opp-peak-bw not found\n",
>
> s/opp-peak-bw/opp-peak-kBps/

Thanks. Will fix.

-Saravana